As a home network protocol, there are universal plug and play (UPnP) technology and digital living network alliance (DLNA) technology.
The universal plug and play (UPnP) technology and the digital living network alliance (DLNA) technology allow controls and services between home appliances of various manufacturers. Especially, the UPnP technology allows compatible AV service and control between audio-visual (AV) devices. As the compatible AV service, there are media streaming, uploading, and downloading.
DLNA, as a home network device, regulates a digital media server (DMS), a digital media player (DMP), a digital media renderer (DMR), a digital media controller (DMC), and a digital media printer (DMPr), and, as a mobile portable device, regulates a mobile digital media server (M-DMS), a mobile digital media player (M-DMP), a mobile digital media uploader (M-DMU), a mobile digital media downloader (M-DMD), and a mobile digital media controller (M-DMC).
Hereinafter, in terms of concept, the DMS covers the M-DMS, the DMP covers the M-DMP, and the DMC covers the M-DMC.
The UPnP classifies such devices into control points (CPs) and devices. The DMC and the DMP are classified into CPs, and the DMR, the DMS, and DMPr are classified into devices. Hereinafter, the mentioned control device or controller may indicate a CP of the UPnP. Hereinafter, the mentioned control target device may indicate a device of the UPnP.
Moreover, the DLNA defines a 2-box model and a 3-box model.
The 2-box model includes a DMP and a DMS. In the 2-box model, the DMP allows a user to find and play a browsed and distributed content by using the DMS.
The 3-box model includes a DMC, a DMS, and a DMR. In the 3-box model, the DMC allows a user to find a content of the DMS, which is to be played in the DMR.
Devices following the UPnP and the DLNA exchange commands through internet protocol (IP) networking. That is, one of AV devices connected to the same network provides AV service to the other devices and receives AV service from other devices, and also controls other devices and is controlled by other devices.
Especially, in the 3-box model, a media renderer receives media content from a media server according to a control of a controller and plays the received media content. However, when a media content to be played by a control of a controller is transited, since a media renderer receives media content from a media server according to a transit command, time delay at the transition occurs, so that seamless transition may not be provided.
This occurs when the media renderer is a device separated from a media server. Therefore, this is still an issue in the 2-box model.
When the media renderer is a device separated from a media server, methods of providing seamless transition between media content are suggested but these methods do not have flexibility that may be applicable to various situations.